Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$142.49	4.661%	$149.1315	$149.13	$149.15	$149.10
Purchase #2	$233.61	11.134%	$259.6201	$259.62	$259.60	$259.60
Purchase #3	$215.66	6.360%	$229.376	$229.38	$229.40	$229.40
Purchase #4	$71.51	7.180%	$76.6444	$76.64	$76.65	$76.60
Purchase #5	$82.76	9.435%	$90.5684	$90.57	$90.55	$90.60
Purchase #6	$185.52	11.447%	$206.7565	$206.76	$206.75	$206.80
Purchase #7	$119.71	10.640%	$132.4471	$132.45	$132.45	$132.40
7 purchase totals =	$1,051.26		$1,144.5440	$1,144.55	$1,144.55	$1,144.50